A small patch antenna using metamaterial transmission line based on conventional logarithmic spiral resonators

Based on the concept of the LSR-MTM transmission line a LSR-MTM patch antenna is presented. In order to use LSR this kind of antenna does not need any through connection with the ground plane to reduce the size of the antenna, which simplifies the fabrication of the antenna. Therefore it could be a useful candidate for small patch antennas. A prototype of the LSR-MTM patch antenna is fabricated and it is shown that the size of the antenna compared to a conventional patch antenna at the same resonance frequency is reduced by 46.63%. The resonance frequency of the prototype antenna and its fractional bandwidth are 2.025 GHz and 4.4% respectively. Furthermore, the orientation of the LSR is investigated and it is shown that different resonance frequencies can be achieved by changing the orientation of LSR with an identical patch on the upside of the antenna. A gain of about 7.3dBi was measured. This shows that a similar performance to that of conventional patch antennas can be achieved with about half the size.